<!DOCTYPE html>
<html>

<head>
    <title>CSS 下拉内容的对齐方式</title>
    <meta charset="utf-8">
    <style>
        .dropbtn {
            background-color: #4CAF50;
            color: white;
            padding: 16px;
            font-size: 16px;
            border: none;
            cursor: pointer;
        }

        .dropdown {
            position: relative;
            display: inline-block;
        }

        .dropdown-content {
            display: none;
            position: absolute;
            right: 0;
            background-color: #f9f9f9;
            min-width: 160px;
            box-shadow: 0px 8px 16px 0px rgba(0, 0, 0, 0.2);
        }

        .dropdown-content a {
            color: black;
            padding: 12px 16px;
            text-decoration: none;
            display: block;
        }

        .dropdown-content a:hover {
            background-color: #f1f1f1;
        }

        .dropdown:hover .dropdown-content {
            display: block;
        }

        .dropdown:hover .dropbtn {
            background-color: #3e8e41;
        }
    </style>
</head>

<body>

    <h2>下拉内容的对齐方式</h2>
    <p>left 和 right 属性指定了下拉内容是从左到右或从右到左。</p>

    <div class="dropdown" style="float:left;">
        <button class="dropbtn">左</button>
        <div class="dropdown-content" style="left:0;">
            <a href="#">菜鸟教程 1</a>
            <a href="#">菜鸟教程 2</a>
            <a href="#">菜鸟教程 3</a>
        </div>
    </div>

    <div class="dropdown" style="float:right;">
        <button class="dropbtn">右</button>
        <div class="dropdown-content">
            <a href="#">菜鸟教程 1</a>
            <a href="#">菜鸟教程 2</a>
            <a href="#">菜鸟教程 3</a>
        </div>
    </div>

</body>

</html>